JERUSALEM - Israeli forces have raided the biggest Palestinian town in the West Bank. Palestinians are accusing Israel of torpedoing efforts to get the stalled peace process back on track.

Israeli troops in dozens of jeeps and armored vehicles stormed into the West Bank town of Nablus, placing about 50,000 Palestinians under curfew. Soldiers conducted house-to-house searches, and residents were ordered to stay indoors.

The raid focused on the Casbah, or Old City, a densely populated area of narrow alleyways, apartment buildings and markets.

The army said the operation could last several days and is aimed at uncovering bomb factories and arresting wanted Palestinian militants. The incursion comes a few days after a would-be suicide bomber was captured near Tel Aviv.

“We will defend our citizens and we will pinpoint against all of those terror cells in the West Bank who try to attack us,” said Israeli spokeswoman Miri Eisen.

“We condemn this Israeli raid. It is absolutely uncalled for. We do not need to go back to the cycle of violence,” said Palestinian legislator Saeb Erekat.

But Israel has repeatedly complained that Mr. Abbas has failed to crack down on militants operating from territory under his control. Israeli analyst Dan Schueftan says that leaves Israel with little choice.

“Israel will have to continue and take military action just to keep the level of terrorism below the level that is insufferable from an Israeli point of view,” said Schueftan.

The army says it launched the Nablus operation after receiving intelligence information that terrorists in the city were planning a wave of suicide bombings in Israeli cities.